1. Field of the Invention
The present invention relates to integrated circuits, and more particularly to output circuits of integrated circuits.
2. Description of the Related Art
An integrated circuit may provide an output signal having a selected signal format by including duplicate output bond pads. Each bond pad (or pair of pads for differential formats) is coupled to a corresponding output driver circuit. During a packaging process, the desired pads are bonded to package pins and the unconnected pads and driver are unused. While this approach allows one integrated circuit to generate multiple signal formats, extra area is consumed by the unused output driver and pads, and the output signal format must be selected and fixed during the packaging process.
Another technique for providing an output signal having a selected signal format includes designing separate integrated circuits for each output signal format to avoid wasting die area of unused output drivers(s). This approach introduces additional mask costs if the designs are processed using separate mask sets. Like the former technique, the signal format must be selected during the packaging process. Both of the former and latter techniques require additional product inventory because stock must be kept for each part number.
Conversion buffers may be used to provide an interface between input buffers and output drivers having different signal formats. This approach allows one integrated circuit to be used in multiple applications requiring different numbers and types of loads. However, conversion buffers introduce the costs of additional board space and additional clock jitter. For high precision applications, the buffer jitter can significantly degrade system performance.
Accordingly, improved techniques for providing output signals having a selected output signal format are desired.